Homozygous truncation of SIX6 causes complex microphthalmia in humans

To the Editor : Microphthalmia is a highly morbid birth defect that is heterogeneous in etiology (1). A genetic cause of microphthalmia, suspected in many cases, is confirmed in only a minority because of significant locus heterogeneity that has only been partially captured to date. SIX6 is a compelling candidate gene for microphthalmia but no conclusive point mutations have been reported previously. We describe in this communication a multiplex family in which microphthalmia associated with anterior and posterior segment dysgenesis (complex microphthalmia) is caused by a homozygous SIX6 truncating mutation.